Final answer:
The correct answer is C. Water. The range of water available to plants is determined by the amount of moisture present in the soil between its field capacity and the point of permanent wilting, which is crucial for understanding how plants acquire water from the soil.
Step-by-step explanation:
The range of water available to plants is between field capacity and the permanent wilting point.The concept of field capacity and permanent wilting point is fundamental in understanding how soil retains water and its availability for plant use. Field capacity is defined as the amount of soil moisture or water content held in the soil after excess water has drained away and the rate of downward movement has decreased. This capacity indicates the storage capacity of the soil which is useful for plant roots. On the other hand, the permanent wilting point is the point at which the soil is so dry that plant roots are no longer able to sufficiently extract water, causing the plant to wilt and not recover.
Soils with different textures affect how quickly they reach these points. For instance, sandy soils can dry out quickly and hold less water between the range of field capacity and permanent wilting point, whereas clay soils can hold more water but also have poor drainage. Loam soils are often considered best for agriculture due to their balanced structure, which allows for optimal water retention and drainage.
Understanding these soil properties is important to agriculture and horticulture in order to manage irrigation and ensure healthy plant growth.